Volatile Organic Profiles Research Articles

Exploring volatile organic profiles of red pen inks based on gas-chromatography-flame ionization detection (GC-FID) and chemometric methods for forensic investigation purposes

Criminal cases involving questioned documents often cause the loss of a huge amount of money in a country. Red ballpoint pen inks found on threatening notes, or any official documents are potentially encountered by a forensic document examiner as questioned documents. Identifying sources of the questioned ink entries is paramount to revealing the authenticity or sources of the document. Despite the multitude of works being devoted to discriminating pen inks by their sources, very little is focused on the volatile fractions. In this study, the volatile compositional profiles of ten types of red ballpoint pen inks as acquired by gas chromatography-flame ionization detection (GC-FID) were studied using various multivariate exploratory tools. Scores plot of principal component analysis reveals that inter-pen brand variation is higher than the inter-pen type variation. Meanwhile, hierarchical clustering analysis showed that 6 of the 10 pen types and all five pen brands could be discriminated. In conclusion, volatile organic compositions of red pen inks are useful in classifying the pen inks by brands. The outcome of the study will provide vital insight into the potential of volatile organic profiles in discriminating red pen inks sold in Malaysia.

Aromatic Yeasts: Interactions and Implications in Coffee Fermentation Aroma Profiles.

Nontraditional yeasts prevalent in tropical agricultural fermentations such as coffee and cocoa are known to contribute to aroma profiles, yet the functional roles and interactions between the associated microbial consortia in a farm fermentation are unclear. Here, boiled green bean extract (GBE) from green coffee beans was developed as a rich screening medium to deconstruct the microbial consortia and their interactions during the fermentation of dried green coffee beans. When cultivated in coculture with S.cerevisiae on GBE, strain-specific groupings with distinct volatile organic profiles were observed for nontraditional yeasts (e.g., Hanseniaspora spp., Pichia kudriavzevii). Further changes are evident when constructed consortia composed of nontraditional yeast, S.cerevisiae, and Lactococcus lactis var. cremoris were cultured in GBE, and a comparison with abiotically acidified GBE suggests that pH plays a major role in the influence of lactic acid bacteria (LAB) on fermentation aromas. This approach represents a tool for the development of starter culture formulations to create different flavor profiles in coffee fermentation.

A geographical origin assessment of Italian hazelnuts: Gas chromatography-ion mobility spectrometry coupled with multivariate statistical analysis and data fusion approach

Hazelnut is a commodity that has gained interest in the food science community concerning its authenticity. The quality of the Italian hazelnuts is guaranteed by Protected Designation of Origin and Protected Geographical Indication certificates. However, due to their modest availability and the high price, fraudulent producers/suppliers blend, or even substitute, Italian hazelnuts with others from different countries, having a lower price, and often a lower quality. To contrast or prevent these illegal activities, the present work investigated the application of the Gas Chromatography-Ion mobility spectrometry (GC-IMS) technique on the hazelnut chain (fresh, roasted, and paste of hazelnuts). The raw data obtained were handled and elaborated using two different ways, software for statistical analysis, and a programming language. In both cases, Principal Component Analysis and Partial Least Squares-Discriminant Analysis models were exploited, to study how the Volatile Organic Profiles of Italian, Turkish, Georgian, and Azerbaijani products differ. A prediction set was extrapolated from the training set, for a preliminary models’ evaluation, then an external validation set, containing blended samples, was analysed. Both approaches highlighted an interesting class separation and good model parameters (accuracy, precision, sensitivity, specificity, F1-score). Moreover, a data fusion approach with a complementary methodology, sensory analysis, was achieved, to estimate the performance enhancement of the statistical models, considering more discriminant variables and integrating at the same time further information correlated to quality aspects. GC-IMS could be a key player as a rapid, direct, cost-effective strategy to face authenticity issues regarding the hazelnut chain.

Coffee-roasting variables associated with volatile organic profiles and sensory evaluation using multivariate analysis

A multivariate analysis investigated the operational variables of a professional roaster, the volatile chemical composition of roasted specialty coffee and how they correlate with the sensory evaluation of the final beverage, which directly affects the commercial value of the product. The experimental planning elicited 38 distinct roasting profiles that variegate (i) drum initial temperature (160 and 200 °C); (ii) drum air-flow ventilation opening (25-50-100 and 25-75-100 % – numbers show the percentage of opening for ventilation throughout the roasting); (iii) drum rotation speed (40 and 65 rpm); (iv) fuel gas flow/pressure increase into burners (0.5 and 1.0 mbar min−1); (v) roasting time after bean cracking (1.0 and 2.0 min). After roasting, 108 volatile organic compounds (VOC) were measured by SPME-GC-MS in the aroma of the roasted coffees. Principal component analysis (PCA) correlated VOC profiles, the operational variables of the coffee roaster and sensory evaluation. PCA from either sensory or chemical analysis data indicated “time after bean cracking” as the major influence and 30 seconds are enough to diminish a couple of points in coffee quality within the Specialty Coffee Association classification. The interaction between variables “fuel increase ramp” and “time after bean cracking” also altered VOC profiles and separated distinct roasting groups. PCA from chemical analysis delivered better separation between sample sets than PCA from sensory evaluation concerning either “time after bean cracking” or the interaction “fuel increase ramp” versus “time after bean cracking”. The coupling of sensory, chemical and operational data and their interpretation through multivariate analysis can improve the knowledge of how the operational procedures affect the final quality of coffee.

Selection of Non-Saccharomyces Wine Yeasts for the Production of Leavened Doughs

Background: Non-conventional yeasts (NCY) (i.e., non-Saccharomyces) may be used as alternative starters to promote biodiversity and quality of fermented foods and beverages (e.g., wine, beer, bakery products). Methods: A total of 32 wine-associated yeasts (Campania region, Italy) were genetically identified and screened for decarboxylase activity and leavening ability. The best selected strains were used to study the leavening kinetics in model doughs (MDs). A commercial strain of Saccharomyces cerevisiae was used as the control. The volatile organic profiles of the inoculated MDs were analyzed by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). Results: Most of strains belonged to the NCY species Hanseniaspora uvarum, Metschnikowia pulcherrima, Pichia kudriavzevii, Torulaspora delbruekii, and Zygotorulaspora florentina, while a few strains were S. cerevisiae. Most strains of H. uvarum lacked decarboxylase activity and showed a high leaving activity after 24 h of incubation that was comparable to the S. cerevisiae strains. The selected H. uvarum strains generated a different flavor profile of the doughs compared to the S. cerevisiae strains. In particular, NCY reduced the fraction of aldehydes that were potentially involved in oxidative phenomena. Conclusions: The use of NCY could be advantageous in the bakery industry, as they can provide greater diversity than S. cerevisiae-based products, and may be useful in reducing and avoiding yeast intolerance.

Authentication of recycled plastic content in water bottles using volatile fingerprint and chemometrics

The environment is threatened by the continuously increasing volume of plastic residue. Plastic recycling is an interesting alternative to mitigate this problem. However, recycled plastic products may have pollutants from their recycling process, collecting system and/or previous life which may hurt consumers health, thus making it key to authenticate and characterize recycled materials. An innovative non-targeted methodology by means of static headspace gas chromatography-mass spectrometry (SHS-GC-MS) has been developed to measure the volatile organic profile of virgin polyethylene terephthalate (PET) and with diverse content of recycled PET samples. A home-made MS database, with 161 organic compounds characteristics from plastic materials based on the literature, was made. Seventeen of those compounds were found in the studied samples and identified by matching their MS spectra with MS database libraries. These compounds are mainly aldehydes (pentanal, hexanal, heptanal, octanal, nonanal and decanal), and benzene derivatives (styrene, p-xylene, benzaldehyde, methylbenzene, and 1,2-dichlorobenzene) which we found to be the common in the samples of recycled PET. The combination of the dataset consisting in the peak area of the detected species by SHS-GC-MS and the use of chemometrics shown to be a valuable methodology for the discrimination between virgin PET samples and those with different recycled PET content based on their volatile profile. In addition, a novel strategy applying a statistical model based on partial least squares (PLS) regression was proposed, for the first time, to quantify the recycled plastic content in the PET samples.

Characterization of Berry Aromatic Profile of cv. Trebbiano Romagnolo Grapes and Effects of Intercropping with Salvia officinalis L.

Volatile organic compounds (VOCs) are secondary metabolites responsible for the aroma of grapes and the quality of wine. Apart from genetics, agronomic practices may impact the aroma composition and the concentration of volatiles in grape berries. The possible influence of intercropping with medicinal aromatic plants (MAPs) on the VOCs in grape berries’ profile has been poorly explored. Trebbiano Romagnolo is a white Vitis vinifera cultivar cultivated within the Italia region Emilia-Romagna. The study investigated, for the first time, the volatile organic profile of Trebbiano Romagnolo berries as well as the possible influences of intercropping with sage (Salvia officinalis L.) on the volatile composition of grape berries. A total of 48 free and bound aroma compounds were identified using solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS). In the free aroma fraction, the main classes were C6 derivatives, alcohols, and benzenes, while in the bound aroma fraction, the major classes were benzenes, C13 norisoprenoids, and terpenes. The results obtained in this experiment indicate that intercropping with Salvia officinalis may influence volatile compounds in grape berries, an interesting result in cultivars considered neutral such as Trebbiano Romagnolo, providing new insights for exploring the complexity of the terroir and the role of agroecological strategies.

Direct Classification of Volatile Organic Compounds in Heat-Treated Glutathione-Enriched Yeast Extract by Headspace-Gas Chromatography-Ion Mobility Spectrometry (HS-GC-IMS)

Yeast extract (YE) is tremendously used as a flavor enhancer in foods because of its composition. However, different types of YE have different aromatic profiles. This study focuses on the thermal treatment of glutathione-enriched yeast extract (GSH-YE) at different temperatures with the addition of Maillard precursors to investigate any change in its volatile organic profile. Headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) was utilized for the instrumental analysis. A total number of 104 volatile compounds were analyzed through this approach. Qualitative and quantitative analysis of the samples were made in order to calculate the concentration of volatile compounds in samples. Sensory evaluation was performed to compare the overall aroma descriptions with the volatile profile of the heat-treated samples. Sensory scores revealed that an increase in the thermal temperature significantly affected the meaty and roasted aroma of GSH-YE. Many sulfur-containing volatile compounds including 2-methyl-3-furanthiol, 2-furfurylthiol, 2-methyl-3-(methylthio)furan, dimethyl trisulfide, 2-acetylthiazol, and some furans and pyrazines related to meaty and roasted odor notes were reported in this study. Significant increase in the amounts of furfural and dimethyl sulfide was observed in samples having higher thermal temperatures as compared with the control treatment. The temperature of 100 °C with adequate amounts of Maillard precursors in GSH-YE was considered an optimal condition for generating ample amounts of 2-methyl-3-methylthiofuran and 2-furfurylthiol. The 3D graphical data confirms the potential application of HS-GC-IMS as a more potent instrumental approach in the determination of volatile compounds in yeast extract.

Total replacement of dietary fish meal with black soldier fly (Hermetia illucens) larvae does not impair physical, chemical or volatile composition of farmed Atlantic salmon (Salmo salar L.).

The aquafeed sector has been replacing conventional dietary ingredients with more economic and eco-friendly ingredients. Insects embody a promising alternative as a result of being highly nutritious and showing traits leading to a circular bioeconomy. Atlantic salmon (Salmo salar L.) at the sea-water stage were fed diets with a partial or complete substitution of fishmeal with meal of Hermetia illucens larvae reared on a media containing Ascophyllum nodosum mixed with organic wastes (60:40). The present study aimed to assess the quality of fillets by characterizing its physico-chemical traits with conventional and innovative methods, such as the proton transfer reaction-time of flight-mass spectrometer technique, allowing the analysis of samples at room temperature. Finally, steamed fillets underwent a consumer test to investigate the liking of consumers and their intention of re-consumption. The main findings showed that a complete dietary substitution of fishmeal with H. illucens larvae meal did not impair the physico-chemical quality of A. salmon fillets. Notably, neutral n-3 polyunsaturated fatty acids (PUFA) slightly but significantly increased in the fillets of A. salmon fed H. illucens, also as a result of the additional fish oil present in the diets containing insect. The volatile organic profile was not altered by the different diets. The consumer-liking test revealed that Italian consumers appreciated the tested salmon irrespective of the administered feed. Tailoring the insect fatty acid profile by rearing the larvae on a PUFA-rich substrate, coupled with a dietary modulation of the oily source, can successfully maintain or even increase the cardioprotective characteristics of fillets. © 2019 Society of Chemical Industry.

Towards Closed Loop Control of Cell Production: Analysis of Volatile Organic Profiles in Stem Cells By Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry

Personalized cell therapies have demonstrated clinical benefits and have shown great promise in solving monogenetic diseases. Despite these documented benefits, commercialization has been limited due to challenges including manufacturing, characterization, quality control, and stability. Previous work has demonstrated the potential of gas chromatography coupled with mass spectrometry to evaluate the volatile organic profiles of cell cultures. However, due to the complexity of the medium and the intensity of the identified peaks, the data has been limited. This work reports on the development of a method to investigate the volatile organic compound (VOC) profiles of stem cells using the increased resolution of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC/TOF MS) for the purpose of stem cell characterization, growth status analysis, and identification of critical quality attributes. Mesenchymal stem cells (MSCs), from a variety of sources, were cultured and analyzed throughout their growth process. Samples of spent cell culture media were collected during cell passaging and incubated prior to analyzing the headspace above the media. Solid phase microectraction (SPME) was used as to concentrate the VOCs present in the sample headspace. The use of SPME, in conjunction with GCxGC/TOF MS allowed for an expanded understanding of the MSC volatilome and the development of relevant VOC profiles. The effect of growth media, cell source, growth status, and confluency on the chemicals identified in the VOC profiles was studied. Non-targeted analysis revealed more than 100 compounds of potential interest identified through spectral deconvolution and the NIST library of electron impact spectra. The identities of the compounds of interest was validated through the use of analytical standards. Principal component analysis (PCA) was used to reduce dimensionally and visualize variance in the data. Hierarchical clustering analysis was employed to assess relatedness between samples based on their volatile organic profiles. The distinct variations between the volatilomes is able to distinguish different cell sources and growth statuses. While this work is in its preliminary stage, it lays the foundation for closed loop control of cell manufacturing. The identification of critical quality attributes and their associated VOC profiles, using powerful laboratory equipment is the first step in closing the manufacturing loop. With the newfound knowledge, miniaturized in-line sensors can be developed to allow for complete control of the cell manufacturing process, assuring not only a high quality product, but an efficient manufacturing process as well. Figure 1

Rapid discrimination of fungal strains isolated from human skin based on microbial volatile organic profiles

Studies of the microbiota of human skin have gained attention mainly because of its high complexity. Volatile metabolites that emerge from the microbiota play a significant role in fungus metabolism, acting on fungal development, defense, and protection against stress, communication, and pathogenicity. The present study evaluated volatile organic profiles, based on headspace–solid-phase microextraction–gas chromatography–mass spectrometry. We sought to define the optimal experimental conditions for such identification. Chromatograms from 15 fungi were evaluated and discriminated by principal component analysis. The volatile metabolite profiles that were putatively identified in the present study (e.g 2‑isopropyl‑5‑methyl‑cyclohex‑3‑en‑1‑one, 3/2‑methyl‑1‑butanol, isopentyl ethanoate, phenyl ethanol) allowed the discrimination of different microorganisms from human skin. The present methodology may be a more rapid way of identifying microorganisms compared with conventional methods of microbiological identification.

Effects of dairy system, herd within dairy system, and individual cow characteristics on the volatile organic compound profile of ripened model cheeses

The objective of this work was to study the effect of dairy system, herd within dairy system, and characteristics of individual cows (parity, days in milk, and daily milk yield) on the volatile organic compound profile of model cheeses produced under controlled conditions from the milk of individual cows of the Brown Swiss breed. One hundred fifty model cheeses were selected from 1,272 produced for a wider study of the phenotypic and genetic variability of Brown Swiss cows. In our study, we selected 30 herds representing 5 different dairy systems. The cows sampled presented different milk yields (12.3–43.2kg/d), stages of lactation (10–412 d in milk), and parity (1–7). In total, 55 volatile compounds were detected by solid-phase microextraction and gas chromatography-mass spectrometry, including 14 alcohols, 13 esters, 11 free fatty acids, 8 ketones, 4 aldehydes, 3 lactones, 1 terpene, and 1 pyrazine. The most important sources of variation in the volatile organic profiles of model cheeses were dairy system (18 compounds) and days in milk (10 compounds), followed by parity (3 compounds) and milk yield (5 compounds). The model cheeses produced from the milk of tied cows reared on traditional farms had lower quantities of 3-methyl-butan-1-ol, 6-pentyloxan-2-one, 2-phenylethanol, and dihydrofuran-2(3H)-one compared with those reared in freestalls on modern farms. Of these, milk from farms using total mixed rations had higher contents of alcohols (hexan-1-ol, octan-1-ol) and esters (ethyl butanoate, ethyl pentanoate, ethyl hexanoate, and ethyl octanoate) and lower contents of acetic acid compared with those using separate feeds. Moreover, dairy systems that added silage to the total mixed ration produced cheeses with lower levels of volatile organic compounds, in particular alcohols (butan-1-ol, pentan-1-ol, heptan-1-ol), compared with those that did not. The amounts of butan-2-ol, butanoic acid, ethyl-2-methylpropanoate, ethyl-3-methylbutanoate, and 6-propyloxan-2-one increased linearly during lactation, whereas octan-1-ol, 3-methyl-3-buten-1-ol, 2-butoxyethanol, 6-pentyloxan-2-one, and 2,6-dimethylpyrazine showed a more complex pattern during lactation. The effect of the number of lactations (parity) was significant for octan-1-ol, butanoic acid, and heptanoic acid. Finally, concentrations of octan-1-ol, 2-phenylethanol, pentanoic acid, and heptanoic acid increased with increasing daily milk yield, whereas dihydrofuran-2(3H)-one decreased. In conclusion, the volatile organic compound profile of model cheeses from the milk of individual cows was affected by dairy farming system and stage of lactation and, to lesser extent, by parity and daily milk yield.

Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry for Analysis of VOCs Produced by Phytophthora cinnamomi.

Volatile organic compounds (VOCs) from Phytophthora cinnamomi-infected lupin seedlings were collected by headspace solid-phase microextraction (HS-SPME). The sampling was done 28 to 44, 52 to 68, and 76 to 92 h after inoculation (HAI). The HS-SPME samples were analyzed by gas chromatography-flame ionization detector (GC-FID) to assess the differences in volatile compounds between the P. cinnamomi-infected lupin seedlings and the control. Three specific peaks were identified after 52 to 68 h with the infected lupin seedlings, at which time there were no visible aboveground symptoms of infection. Subsequently, the VOCs of five different substrates (V8A, PDA, lupin seedlings, soil, and soil + lupin seedlings) infected with P. cinnamomi and the corresponding controls were analyzed by gas chromatography-mass spectrometry (GC/MS). A total of 87 VOCs were identified. Of these, the five most abundant that were unique to all five inoculated substrates included: 4-ethyl-2-methoxyphenol, 4-ethylphenol, butyrolactone, phenylethyl alcohol, and 3-hydroxy-2-butanone. Therefore, these metabolites can be used as markers for the identification of P. cinnamomi in different growing environments. Some VOCs were specific to a particular substrate; for example, 2,4,6-rrimethyl-heptanes, dl-6-methyl-5-hepten-2-ol, dimethyl trisulfide, 6,10-dimethyl- 5,9-undecadien-2-ol, and 2-methoxy-4-vinylphenol were specific to P. cinnamomi + V8A; heptanes and 5-methyl-3-heptaneone were specific to P. cinnamomi + PDA; 3-methyl-1-butanol, ethyl acetate, 2-methyl-propanoic acid, ethyl ester, and ethyl ester 2-methyl-butanoic acid were specific to P. cinnamomi-inoculated lupin seedlings; and benzyl alcohol and 4-ethyl-1, 2-dimethoxybenzene were only detected in the headspace of inoculated soil + lupin seedlings. Results from this investigation have multiple impacts as the volatile organic profiles produced by the pathogen can be utilized as an early warning system to detect the pathogen from contaminated field soil samples. Data from this investigation have also illuminated potential metabolic pathways utilized by the oomycete during infection which may serve as potential targets for the development of specific control strategies.

The Use of SIFT-MS in Profiling the Faecal Volatile Metabolome in Horses with Colic: A Pilot Study

SIFT-MS is used for the first time in profiling the volatile organic profile in faecal headspace in two groups of horses admitted to an equine hospital, one group with acute intestinal disease (colic) affecting the large colon, plus a control group of similarly managed horses admitted for non-gastrointestinal/metabolic reasons (e.g. acute orthopaedic injury). Compounds in faecal headspace which show statistically significant concentration differences between the groups are acetone and methanol. In addition, some ions at various m/z values show significantly different ion counts between the groups. Further information may be gleaned by using multivariate statistics in evaluating the differences between the two horse groups. Principal components analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were evaluated for reducing the dimensionality of the SIFT-MS data, and OPLS-DA was found to be best at discriminating between the groups, particularly with SIFT-MS data acquired using the H3O+ precursor ion. Analysis of these data also show the significance of ammonia as a discriminating ion. These results show that SIFT-MS may potentially be used on the headspace of horse faecal samples for detecting altered microbial fermentation associated with acute intestinal disease of the colon. Keywords: SIFT-MS, metabolic profiling, horse volatile metabolome.

Prediction of mold contamination from microbial volatile organic compound profiles using solid phase microextraction and gas chromatography/mass spectrometry

An integrated chemical and microbiological approach was used to develop a new sampling and analytical methodology to characterize the fungal load of a contaminated area or building. A set of microbial volatile organic compound (MVOC) profiles were developed with corresponding bioaerosol measurements as input–output pairs for a discriminant to predict the presence or absence of mold contamination in indoor environments. Spore collection to characterize the indoor air quality of the residences and buildings was performed using an Anderson N6 impactor. Simultaneously, solid phase microextraction was used as a passive sampling device to collect VOCs from the air for GC/MS analysis. The volatile organic signatures that molds emit as reflected by the gas chromatographic profiles were compared to the impactor data collected from each sampling site. By comparing the bioaerosol data to the volatile organic profiles, a discriminant could be trained to classify a residence with potential mold growth based on its MVOCs.

Multiple Self Organising Maps (mSOMs) for simultaneous classification and prediction: Illustrated by spoilage in apples using volatile organic profiles

Self Organising Maps (SOMs) have been modified and extended for various applications. This paper employed multiple SOMs (mSOMs) in supervised manner for multitasking involving simultaneous classification and prediction providing more information on a sample. This was demonstrated on the GC–MS dataset of apple spoilage where the volatile organic compounds (VOCs) of two groups of apples, control and inoculated, were monitored over 2 to 10 days. Multiple SOMs were used to determine whether a sample is a control or an inoculated apple and at the same time the spoilage day is predicted, i.e. how many days an apple has been left with or without inoculation. Multiple SOMs are different from traditional supervised SOMs; in mSOMs, samples are divided into classes for training on different maps. This approach of SOMs does not require optimisation of the scaling value however, it is important to make sure that the clustering qualities of mSOMs are comparable. Growing Self Organising Maps (GSOMs) was incorporated to automatically determine the suitable map size with comparable clustering qualities based on the mean quantization error. The findings demonstrated that mSOMs can be potentially applied for simultaneous analysis allowing more information to be retrieved on a sample reducing the overall computational time of an analysis.

Rapid characterization of dry cured ham produced following different PDOs by proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS)

In the present study, the recently developed proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS) technique was used for the rapid characterization of dry cured hams produced according to 4 of the most important Protected Designations of Origin (PDOs): an Iberian one (Dehesa de Extremadura) and three Italian ones (Prosciutto di San Daniele, Prosciutto di Parma and Prosciutto Toscano). In total, the headspace composition and respective concentration for nine Spanish and 37 Italian dry cured ham samples were analyzed by direct injection without any pre-treatment or pre-concentration. Firstly, we show that the rapid PTR-ToF-MS fingerprinting in conjunction with chemometrics (Principal Components Analysis) indicates a good separation of the dry cured ham samples according to their production process and that it is possible to set up, using data mining methods, classification models with a high success rate in cross validation. Secondly, we exploited the higher mass resolution of the new PTR-ToF-MS, as compared with standard quadrupole based versions, for the identification of the exact sum formula of the mass spectrometric peaks providing analytical information on the observed differences. The work indicates that PTR-ToF-MS can be used as a rapid method for the identification of differences among dry cured hams produced following the indications of different PDOs and that it provides information on some of the major volatile compounds and their link with the implemented manufacturing practices such as rearing system, salting and curing process, manufacturing practices that seem to strongly affect the final volatile organic profile and thus the perceived quality of dry cured ham.

Determination of Volatile Organic Profiles and Photochemical Potentials from Chemical Manufacture Process Vents

The main objective of this study was to monitor the volatile organic compounds (VOCs) in the stack gas released from organic chemical industrial plants to determine emission factors. Samples from 52 stacks, with or without air pollution control devices (APCDs), from seven industrial processes were taken and VOCs measured using U.S. Environmental Protection Agency (EPA) Method 18. These 7 processes, including 26 plants, were the manufacturers of acrylonitrile–butadiene–styrene (ABS), polyvinyl chloride (PVC), polystyrene (PS), acrylic resin (ACR), vinyl chloride (VC), para–terephthalic acid (PTA), and synthetic fiber (SYF). The results clearly indicate significant variations of emission factors among the various industrial processes, particularly emission factors for those without APCDs. As expected, those with APCDs yield much less emission factors. Regardless of those with or without APCDs, the order of manufacturing processes with regard to VOC emission factors is SYF > ABS > PS > ACR > PTA > PVC > VC. The emission factors for some processes also differ from those in EPA–42 data file. The VOC profiles further indicate that some VOCs are not listed in the U.S. VOC/Particulate Matter Speciation Data System (SPECIATE). The potential O3 formation is determined from the total amount of VOC emitted for each of seven processes. The resultant O3 yield varied from 0.22 (ACR) to 2.33 g O3 g–1 VOC (PTA). The significance of this O3 yield is discussed.

The relationship between volatile organic profiles and emission sources in ozone episode region—a case study in Southern Taiwan

This study investigates the relationship between volatile organic profiles in the atmosphere and emission sources in an ozone non-attainment in region Southern Taiwan. Dynamometer test of vehicles and stack sampling from industrial facilities were conducted to obtain the fingerprints of emissions from on-road mobile sources and stationary sources, respectively. In addition, field sampling of non-methane organic compounds (NMOC) concentration at monitoring stations during episode seasons were also collected by canisters. The influences of different emissions sources on airborne concentrations were estimated by back-trojectory analysis and chemical mass balance model (CMB 8.0) calculation. Field measurement data indicated that the daily average concentration of NMOC ranges between 26.4 and 69.8 ppb at different sites. The mass fraction for paraffins, oleffins and aromatics in airborne samples at these sites were 28–47%, 7–12% and 41–52%, respectively. Toluene was the dominant species among these species, followed by isopentane, n-butane and 1,2,4-trimethylbenzene. The source apportionment of airborne NMOC in the ozone non-attainment region, based on CMB simulation, is passenger cars (28–51%), motorcycles (9–24%), industrial sources (14–33%), solvent application (13–46%) and biogenic emissions (<1–2.4%), respectively. Both field measurement and model analysis showed that the vehicle exhaust and industrial emission are the dominant contributors of NMOC in the region.

Volatile Organic Profiles and Photochemical Potentials from Motorcycle Engine Exhaust

This study surveyed emissions from 2- and 4-stroke new and in-use motorcycles. Emission tests were carried out on a dynamometer following the designated test procedure of the Economic Commission for Europe (ECE). Samples were derived during various driving stages, which included idle, acceleration, 30 km/hr cruise, 50 km/hr cruise, and deceleration. All test motorcycles (10 new and 15 in-use) complied with Taiwan Environmental Protection Administration’s Phase III Motorcycle Emission Standards. The dominant volatile organic carbon (VOC) species were isopentane (53 and 295 mg/km, 2- and 4-stroke, respectively), 2-methylpentane (75 and 83 mg/km), 3-methylpentane (34 and 66 mg/km), and toluene (30 and 100 mg/km). The VOC emission factors for the 2-/4-stroke motorcycles were 311/344 (new) and 1479/433 (inuse) mg/km, respectively. In addition, the dominant carbonyl species for the new and in-use motorcycles were formaldehyde (0.4 and 0.7 mg/km, respectively), acetaldehyde (0.6 and 1.2 mg/km), and acetone (0.5 and 0.7 mg/km). The carbonyl compound emission factors for the 2- and 4-stroke motorcycles were 3.2/3.1 (new) and 5.3/4.6 (in-use) mg/km, respectively. The ozone formation potentials, based on an ECE test cycle, show that the values from the in-use motorcycles were higher than those from the new motorcycles. The dominant VOC species for the ozone formation potential were propylene (65 and 502 mg-O3 /km, respectively), isopentane (98 and 501 mg-O3 /km), 2-methylpentane (152 and 167 mg-O3 /km), 3-methylpentane (79 and 253 mg-O3 /km), and toluene (127 and 398 mg-O3 /km). Further, the dominant carbonyl species were formaldehyde (4.1 and 6.2 mg-O3 /km, new and in-use, respectively) and acetaldehyde (4.8 and 9 mg-O3 /km).